`datetime.timedelta` serde cannot deserialize integer payloads, crashing scheduler during DeadlineAlert DAG-run creation

### Under which category would you file this issue?

Task SDK

### Apache Airflow version

3.3.0

### What happened and how to reproduce it?

The scheduler crashes while creating an asset-triggered DAG run for a DAG with a `DeadlineAlert` interval of `timedelta(minutes=45)`.

The serialized DAG payload observed in the scheduler traceback contains:

```python
{
"__classname__": "datetime.timedelta",
"__version__": 2,
"__data__": 2700,
}
```

The SDK datetime deserializer only accepts `str | float` for `datetime.timedelta`:

```python
if cls is datetime.timedelta and isinstance(data, str | float):
return datetime.timedelta(seconds=float(data))
```

Since `2700` is an `int`, deserialization raises:

```text
TypeError: unknown date/time format datetime.timedelta
```

The exception is unhandled in scheduler DAG-run creation and terminates the scheduler process.

### Minimal reproduction

```python
from datetime import timedelta

from airflow.sdk.serde import CLASSNAME, DATA, VERSION, deserialize

serialized_timedelta = {
CLASSNAME: "datetime.timedelta",
VERSION: 2,
DATA: 2700,
}

assert deserialize(serialized_timedelta) == timedelta(minutes=45)
```

### Actual result

```text
TypeError: unknown date/time format datetime.timedelta
```

### Expected result

```python
timedelta(minutes=45)
```

### Proposed fix

Accept integer second values alongside the already accepted string and float forms.

### What you think should happen instead?

_No response_

### Operating System

_No response_

### Deployment

None

### Apache Airflow Provider(s)

_No response_

### Versions of Apache Airflow Providers

_No response_

### Official Helm Chart version

Not Applicable

### Kubernetes Version

_No response_

### Helm Chart configuration

_No response_

### Docker Image customizations

_No response_

### Anything else?

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

Start at the datetime.timedelta branch in airflow.sdk.serde.deserialize and run the minimal reproduction from the issue. Done means the integer payload 2700 deserializes to timedelta(minutes=45) without the unknown date/time format error, while the existing string and float forms continue to work.

Written by the indexing model from the issue text.